Brush holder assembly and mounting



March 14, 1967 G. G. BLUEMINK 3,309,549

BRUSH HOLDER ASSEMBLY AND MOUNTING Filed July 17. 1965 INVENTOR C heytfzflmzawn( United States Patent 3,309,549 BRUSH HOLDER ASSEMBLY AND MOUNTING Gary G. Bluemink, Racine, Wis., assignor, by mesne as! signments, to MSL Industries, Inc., Racine, Wis., a corporation of Minnesota Filed July 17, 1963, Ser. No. 295,728 11 Claims. (Cl. 310-247) This invention relates to anchoring a brush-holder in a die cast motor shell against either rotative or radial displacement.

In die casting the hollow shell for a series wound or universal motor, a socket is formed at the outer end of the radial opening for the brush holder bushing. This shell differs from conventional practice in that one or more ribs are formed to extend into the socket at the level of the shoulder of the motor shell which constitutes the bottom of the socket. When the prefabricated insulating bushing is pressed into the socket, the rib or ribs bite into the deformable material of the bushing to secure it against rotation. Thereafter a portion of the motor shell is staked over the top of the bushing to secure it against outward movement. Thereby the insert is positively and permanently anchored without requiring the set screws commonly used with less satisfactory results.

In the drawings: 7

FIG. 1 is a side elevational view of a motor made in accordance with this invention, par-ts being broken away.

FIG. 2 is a fragmentary detail view showing the shell and brush holder greatly enlarged and in section.

FIG. 3 is a fragmentary plan view of the motor shell prior to introduction of the brush holder.

FIG. 4 is a fragmentary perspective view of the structure shown in FIG. 3.

FIG. 5 is a fragmentary perspective of the assembly of the motor shell and the brush holder.

The motor shell 6 is generally cylindrical and has bearings such as that shown at 8 for the armature shaft 10. On the shaft is a commutator 12 engaged diametrically by brushes 14. Each brush is reciprocable radially of the shaft in a brush holder comprising a metal sleeve 16 of non-circular cross section set into an insulating bushing 20 of suitable material such asrubbe'r or synthetic resin. The prefabricated insulating bushing 20 is tapped to receive a threaded spring seat plug 2.2 which retains spring 24 for biasing the brush 14 toward the commutator 12.

The motor shell 6 has a radial opening 26 die cast or bored therein to penetrate into the interior of the shell and to receive the bushing 20. A cavity defined by side wall 28 is formed at the outer end of opening 26 for the head portion 30 of the bushing. A shoulder 32 of the sell defines the bottom of the cavity. One or more ribs 34 adjacent the shoulder are formedin the die casting operation to span the angle between the side wall 28 and the bottom 32 of the cavity (FIGS. 3 and 4). The cross sectional dimensions of the opening and the cavity (neglecting the ribs) are complementary to the corresponding parts of the bushing. When the head portion 30 of the bushing 20 is driven into cavity 28 to engage shoulder 32 of the motor shell, the ribs are pressed into the material of the bushing as shown at the left in FIG.

2, thus anchoring the bushing against rotation. The brushes 14 and sleeves 16, being non-circular in cross section, are thereby anchored against rotation.

After the brush holder is firmly seated, a portion 40 of the die cast material of shell 6 is upset or staked inwardly over the head 30 of bushing 20, thus securing the bushing against withdrawal. Since it is securely anchored in the socket, it is also securely impaled on the ribs which preclude rotation. Thus all need for set screws is eliminated. While the anchorage of the brush holder is permanent, the brush and its spring are as readily accessible as heretofore, by unscrewing plug 22.

I claim:

1. The combination with a die cast motor shell having a shaft bearing and generally radial opening and a shoulder about the opening and a cavity beyond the shoulder, of an electrically insulating brush holder in the opening having an enlarged head seated on the shoulder and fitted in the cavity, said shell having an integral portion of limited arcuate extent overhanging the cavity at one side thereof and permanently engaged with said head and constituting means for holding the brush holder in said opening.

2. A combination according to claim 1 in which the brush holder and the opening and cavity are generally circular in cross section, the shell having rib means of generally axial and radial extent and integral with said shoulder and projecting into the cavity at the shoulder and embedded in the brush holder.

3. In a motor or the like, the combination with a brush holder, of a motor shell having an opening in which the brush holder is disposed and having integral portions engaged'with said brush holder and constituting means for restraining it both from rotative and from axial movement.

4. A motor or the like according to claim 3 in which said opening is generally circular in cross section and said shell has an enlarged cavity defined by a shoulder of said shell forming a part of said means, the brush holder having an enlarged head complementary to the cavity and seated on the shoulder, the shell having one of said portions overhanging the brush holder and holding it to said shoulder.

5. A motor or the like according to claim 3 in which said opening and said brush holder are generally circular in cross section, the shell having axially extending rib means projecting in a radial direction from said shell into said opening and embedded in the side of' the brush holder as a part of the means for restraining the brush holder from movement.

6. A method of positioning a brush holder bushing in a motor shell, said method comprising the steps of die casting a motor shell with an opening extending inwardly and at least one rib projecting into the opening, prefabricating an insulating brush holder bushing in a dimension to fit the opening except for the rib, and pressing the bushing into the opening until the rib is embedded in the bushing.

7. A method of positioning a brush holder bushing in a motor shell, which method comprises the steps of die casting a hollow motor shell provided with an outwardly opening cavity and a shoulder at the bottom of the cavity and an opening from the bottom of the cavity into the hollow of said shell, prefabricating a brush holder which includes an insulating bushing dimensionally fitting the opening and the cavity, inserting the bushing into the cavity and opening and seating it against the shoulder, and staking an integral portion of the motor shell over a portion of the bushing for holding it to the shoulder.

8. A method according to claim 7 including the further 7 steps of die casting the motor shell to include ribs extend,- ing into the cavity adjacent the shoulder and reducing the cross sectional dimension of the cavity below that of the corresponding part of the bushing at the locations of the ribs, and exerting sufiicient pressure on the bushing during the said inserting thereof to embed the ribs in the bushing. 9. A method according to claim 7 in which the die casting step includes forming a rib projecting into said cavity and integral with said shoulder, the step of inserting the bushing into the cavity including the exertion of sufiicient pressure to embed the rib in the bushing.

10. In a motor or the like, the combination with a die cast shell having a shaft bearing and a generally radial opening, said shell having a shoulder about the opening and an outwardly opening cavity constituting an enclosed part of the opening beyond the shoulder, said shell having an integral rib projecting into the cavity and integral with the shoulder, of an electrically insulating brush holder in the opening having an enlarged head seated on the shoulder and fitted in the cavity and in which said rib is embedded, said rib securing said brush holder against rotation in the opening, and means for confining the brush holder against axial displacement from the open- '11. A combination according to claim It) in which said last mentioned means comprises an integral portion of the 4 shell having limited arcuate extent about the opening and overhanging the head of the brush holder in permanently confronting relation thereto.

References Cited by the Examiner UNITED STATES PATENTS 842,200 1/1907 Hess 310247 2,372,660 4/ 1945 Cross at al. 310247 2,548,631 4/1951 Stapleton 310247 3,177,388 4/1965 Cook 310-247 MILTON O. HIRSHFIELD, Primary Examiner.

C. W. DAWSON, D. DUGGAN, Assistant Examiners. 

10. IN A MOTOR OR THE LIKE, THE COMBINATION WITH A DIE CAST SHELL HAVING A SHAFT BEARING AND A GENERALLY RADIAL OPENING, SAID SHELL HAVING A SHOULDER ABOUT THE OPENING AND AN OUTWARDLY OPENING CAVITY CONSTITUTING AN ENCLOSED PART OF THE OPENING BEYOND THE SHOULDER, SAID SHELL HAVING AN INTEGRAL RIB PROJECTING INTO THE CAVITY AND INTEGRAL WITH THE SHOULDER, OF AN ELECTRICALLY INSULATING BRUSH HOLDER IN THE OPENING HAVING AN ENLARGED HEAD SEATED ON THE SHOULDER AND FITTED IN THE CAVITY AND IN WHICH SAID RIB IS EMBEDDED, SAID RIB SECURING SAID BRUSH HOLDER AGAINST ROTATION IN THE OPENING, AND MEANS FOR CONFINING THE BRUSH HOLDER AGAINST AXIAL DISPLACEMENT FROM THE OPENING. 